The fastigial nucleas (FN) of the cerebellum when stimulated electrically produces a tachycardia and hypertension that is locked to the stimulus. The role of this nucleus will be investigated by both lesioning FN bilaterally in some dogs and stimulating it chronically in other dogs. Conscious dogs instrumented for measuring of arterial or left ventricular pressure, heart rate, coronary or renal blood flow, will be recorded from during submaximal treadmill exercise before and after lesions are placed into the FN bilaterally. Rationale behind this approach involves the afferent activity from muscles that is delivered to the cerebullum and specifically to the FN. In the absence of this afferent activity, if a deficit in cardiovascular performance with exercise occurs then this is evidence that FN is an autonomic integrator involved with exercise-induced cardiovascular activity. Secondly, the overstimulation of the FN will be performed to examine the potential hypertensive effects. A neurogenic animal model of hypertension has not been avalable to date. Previous models have produced a transient hypertension that reverts to normal with time. Since electrical stimulation of FN produces hypertension, chronic 24 hour stimulation with a duty cycle of several minutes may induce permanent hypertension. Prelimanary evidence indicates the hypertension is initiated and studies are being continued to examine the permanency of that FN-induced hypertension.